Kurzweil's reasoned scenarios of a ""post-biological future"" are as harrowing as any science fiction. That's the appeal of listening on tape to the inventor and MIT professor's provocative speculations on what could occur once computers reach or surpass human-level intelligence--then start to self-replicate. Computers, with their integrated circuit chip complexity, are sneaking up on us on an accelerated curve, he argues, citing the example of chess master Gary Kasparov's shocking loss to IBM's machine Deep Blue in 1997. Do computers represent ""the next stage of evolution""? Will technology create its own next generations? Kurzweil suggests a timeline inhabited by ""neural-nets,"" ""nanobot"" robots and scenarios of virtual reality where sexuality and spirituality become completely simulated. It's bracing and compelling stuff, propelled by the author's own strong egotistical will to prove his version of the future. Reader Sklar is thoughtful, if at times overly heavy on the ironies. Simultaneous release with the Viking hardcover. (Feb.)